Alternator question

[72skylarkcc]

I have a 70 GS 350 hi-comp engine and the alternator has a dual pulley on it. When I pulled the motor, it was running two of the same size alt belts. Does anyone know why this is and is there a way to get one of these refurb. aftermarket. The ones at the local parts store only have a one groove pulley.
Thanks,
Jason

[txgwildcat]

Two groove pulleys are for AC applications, what's yours?

[72skylarkcc]

Mine is a non a/c car. That is what is confusing me. I thought the same thing. When I go home, I need to check and see if I have the wrong pulleys on this thing.